Library for storing data-storage media and having a removable interface module

ABSTRACT

A library for storing a cartridge of data-storage media includes a removable module and a chassis having a module receptacle. Cartridge storage slots are disposed within the chassis, and a media drive is disposed within the removable module. A cartridge transporter is disposed within the chassis and transports the cartridge between one of the cartridge slots and the media drive when the module is inserted within the module receptacle. A library control circuit is disposed within the chassis and controls the cartridge transporter. An interface circuit is disposed within the removable module and electronically interfaces a host computer to the media drive, and, when the removable module is inserted within the module receptacle of the chassis, electronically interfaces the host computer to the library control circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer No. 09/062,522, filed Apr. 17, 1998 U.S. Pat. No. 6,266,574. Thisapplication is also related to U.S. patent application Ser. No.09/062,546, entitled “AN IMPROVED DOOR HINGE” filed on Apr. 17, 1998,now U.S. Pat. No. 6,163,431 and U.S. patent application Ser. No.09/062,662, entitled “LIBRARY FOR STORING DATA-STORAGE MEDIA AND HAVINGAN IMPROVED MEDIA TRANSPORTER” filed on Apr. 17, 1998.

TECHNICAL FIELD

The invention relates generally to electromechanical devices, and morespecifically to a library for storing cartridges of data-storage media,such as magnetic tape, and for providing read/write access to the storedmedia.

BACKGROUND OF THE INVENTION

Because today's computer users often store large volumes of informationon computer systems, it has become increasingly more important to backupthis information to non-volatile storage media, such as magnetic tape orCD-ROM (Compact-Disc Read-Only Memory), and to archive this media sothat the stored information can be easily retrieved. Furthermore, as theamount of a user's backed-up data increases, he often archives thestorage media with the aid of a computer to reduce inventory errors orother errors that may occur when the storage media are manuallyarchived.

One type of device that is often used to archive data-storage media is adata storage library. Typically, the library is interfaced to a hostcomputer system, and includes a media drive for reading data from andwriting data to the storage media, a section for archiving the storagemedia, a section where an operator can load and unload the storagemedia, and a mechanism for transporting the storage media among theload/unload section, the archive section, and the drive. Bycommunicating with or controlling the library, the host computer systemcan keep track of the specific information stored on a particularstorage medium and where in the library the particular storage medium islocated. Thus, when one wishes to retrieve specific archivedinformation, the host computer can control the transport mechanism toretrieve the storage medium containing the specific information and toinsert the storage medium into the media drive so that the computer canaccess the information.

A problem with such data storage libraries is that the on-boardtransport mechanism often requires a relatively large operating space,and thus significantly reduces the amount of space available for mediastorage.

Furthermore, in today's highly computerized environment, there are manyinterface protocols and formats, including SCSI, fiber-channel, andultra-wide interfaces. Therefore, a manufacturer often must make costlyand complex modifications to a library so that it can properly interfacewith a customer's computer system. Alternatively, the manufacturer canproduce different versions of the library, one version for eachinterface protocol and format. But this also significantly increasesoverall manufacturing costs.

Additionally, many computer users want a storage library to berack-mountable so that it can be used to archive information from anentire computer network. But many libraries cannot be rack mountedbecause they are not properly sized to fit within the standard rackspace or because parts of the library, such as an open door, willencroach on the rack space occupied by a component mounted next to thelibrary. Furthermore, many of the libraries that are rack-mountable usethe allotted rack space inefficiently. For example, such libraries mayutilize the full width of the rack space but not the full depth.Moreover, many users want the storage library to be mountable within afraction of a standard rack width but to still have a relatively largeinformation storage capacity.

SUMMARY OF THE INVENTION

In one aspect of the invention, a library is provided for storing acartridge of data-storage media. The library includes a removable moduleand a chassis having a module receptacle. Cartridge storage slots aredisposed within the chassis, and a media drive is disposed within theremovable module. A cartridge transporter is disposed within the chassisand transports the cartridge between one of the cartridge slots and themedia drive when the module is inserted within the module receptacle. Alibrary control circuit is disposed within the chassis and controls thecartridge transporter. An interface circuit is disposed within theremovable module and electronically interfaces a host computer to themedia drive, and, when the removable module is inserted within themodule receptacle of the chassis, electronically interfaces the computerto the library control circuit.

Because the interface circuitry is mounted on a removable module, alibrary can be quickly and easily customized by inserting a module thatprovides the interface used by the customer's host computer or computernetwork. Furthermore, only one version of the base library unit, i.e.,the chassis and the components mounted within the chassis, need bemanufactured. This significantly reduces the cost and complexity of themanufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a computer system including a hostcomputer coupled to a storage library that is in accordance with oneaspect of the invention.

FIG. 2 is an enlarged, exploded isometric view of portions of thestorage library of FIG. 1.

FIG. 3 is a block diagram of the circuitry of the storage library ofFIG. 1.

FIG. 4 is an enlarged, isometric view of the cartridge transporter ofthe storage library of FIG. 1.

FIGS. 5A-5D show the respective positions of the cam mechanism androller mechanism of the cartridge transporter of FIG. 4 during asequence where the transporter retrieves a cartridge from a storage slotand loads the cartridge into a media drive.

FIG. 6 is an enlarged, exploded isometric view of the latch mechanism ofthe storage library of FIG. 1.

FIG. 7 is an enlarged, isometric view of a digital-linear-tape (DLT)cartridge that can be stored by one embodiment of the storage library ofFIG. 1.

FIG. 8 is an enlarged, exploded isometric view of a door assembly forone embodiment of the storage library of FIG. 1.

FIG. 9 is a top view of the door assembly of FIG. 8.

FIGS. 10A-10C are cut-away top views of the door assembly of FIGS. 8 and9.

FIG. 11 is an isometric view of several storage libraries of FIG. 1,that are rack mounted and that incorporate the door assembly of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

A computer system 10, which includes a conventional host computer 12 andan embodiment of a data storage library 14 according to the presentinvention, is shown in FIG. 1. The library 14 communicates with thecomputer 12 and allows the computer 12 to archive data to and retrievedata from one or more data storage media (such as shown in FIG. 7) suchas magnetic-tape cartridges or CD-ROMs. Under control of the computer12, the library 14 receives data from the computer 12, records thereceived data onto a storage medium, and then archives the storagemedium in a particular location within the library 14. To later accessthis data, the computer 12 instructs the library 14 to retrieve thestorage medium from the particular location, to read the data from themedium, and to route the read data back to the computer 12. If thecomputer system 10 is part of a larger computer network, then thecomputer 12 can be configured to allow other network components (notshown in FIG. 1), such as file servers or other computers, to archivedata to and retrieve data from the library 14. Furthermore, althoughshown coupled to the computer 12 in a desktop configuration, the library14 may be rack mounted and connected to a network component other thanthe computer 12.

FIG. 2 is an exploded isometric view of portions of the library 14 ofFIG. 1. The library 14 includes a chassis 16, which has a front opening18 and a rear receptacle 20. In one embodiment of the invention, thelayout and construction of the components within the chassis 16 allowthe dimensions of the chassis 16 to be such that the library 14 can bemounted in a conventional component rack (such as shown in FIG. 11). Forexample, the chassis 16 may be approximately half a rack width wide andsubstantially a fill rack depth long. Furthermore, a door assembly (suchas shown in FIG. 8) may be mounted to the outside of the chassis 16 atthe front opening 18.

A storage-media mailbox 22 is mounted adjacent to the front opening 18of the chassis 16 and includes a number of storage-medium slots 24,which an operator can load and unload via the front opening 18. Althoughthe slots 24 can be constructed to hold any conventional type of astorage medium, for clarity they will be discussed hereinafter ascartridge slots 24, which can hold a conventional magnetic-tapecartridge (such as shown in FIG. 7). A latch mechanism 25 is mountedadjacent to a rear end of the mailbox 22 at the ends of the slots 24facing toward the rear receptacle 20. The latch mechanism 25 includesone latch 26 for each slot 24 to prevent the operator from inserting acartridge too far into a respective slot 24. Conventional optical sensorassemblies 28 are mounted along the sides of the mailbox 22, andgenerate respective optical beams across the slots 24. A broken beamindicates that a cartridge is currently within the respective slot 24.

Furthermore, in one embodiment, additional storage-medium slots 30,which are not part of the mailbox 22, are mounted inside of the chassis16 above the receptacle 20 and provide additional storage capacity. Eachof the slots 30 includes a respective roller 32, which guides acartridge as it is inserted into or removed from a slot 30. Conventionaloptical sensor assemblies 34, which are similar to the sensor assemblies28, are mounted along the sides of the slots 30 within the chassis 16 togenerate respective optical beams across the slots 30. A broken beamindicates that a cartridge is in a respective slot 30.

Each of the slots 24 of the mailbox 22 has an inner opening 38 at therear end of the mailbox, and a top-bottom sensor assembly 36 generates afirst optical beam across all of the inner openings 38 of the slots 24.Each of the slots 30 has an opening 40 located at an end facing towardthe mailbox 22, and the sensor assembly 36 also generates a secondoptical beam across all of the openings 40 of the slots 30. The sensorassembly 36 has the beams located such that a broken first beamindicates that a cartridge is sticking too far out from one of the slots24, and a broken second beam indicates that a cartridge is sticking toofar out from one of the slots 30. The sensor assembly 36 also includes atransporter vertical-position sensor assembly 42, which generates anoptical beam located such that the beam is broken when a storage-mediumtransporter is in a home position. The transporter is positioned withinthe chassis between the mailbox 22 and the slots 30, and is discussedbelow in conjunction with FIG. 4. The sensor assembly 36 also includes acam-position sensor assembly 44, which generates an optical beam that isunbroken when a cam mechanism (such as shown in FIG. 4) of thestorage-medium transporter is in a home position.

A transporter drive assembly 46 moves the storage-medium transporter ina vertical direction so as to align the transporter with a selected oneof the slots 24, the slots 30, or a conventional media drive 48, whichis positioned in the rear receptacle 20 and is discussed below ingreater detail. The drive assembly 46 includes a belt assembly 50, whichis driven by a transporter motor 52. In one embodiment, the motor 52 isa stepper motor, and a worm gear 54 is coupled to the shaft of the motor52 and drives the belt assembly 50.

A roller drive assembly 55 drives a roller mechanism (such as shown inFIG. 4) of the storage-medium transporter. The roller drive assembly 55includes a roller motor 56, which drives a roller drive shaft 58. In oneembodiment, the motor 56 is a stepper motor and drives the shaft 58 viaa worm gear (not visible in FIG. 2).

A cam drive assembly 60 drives the cam mechanism of the storage-mediumtransporter. The cam drive assembly 60 includes a cam motor 62, whichdrives a cam drive shaft 64. In one embodiment, the motor 62 is astepper motor and drives the shaft 64 via a worm gear 66.

A circuit board 68, which is shown in phantom line, is mounted to theinside of the chassis 16 and includes a library control circuit thatcontrols the transporter drive assembly 46, the roller drive assembly 55and the cam drive assembly 60, monitors the condition of the sensorassemblies 28, 34, 36, 42, and 44, and otherwise controls the operationof the library 14 as discussed below in conjunction with FIG. 3.

A module 70 fits within the rear receptacle 20 of the chassis 16. Theconstruction of the module 70 and the rear receptacle 20 allows theoperator to easily insert the module 70 into and remove the module 70from the rear receptacle 20. The module 70 includes the media drive 48and a circuit board 72, which includes an interface circuit (such asshown in FIG. 3) for interfacing the library control circuit on thecircuit board 68 with the computer 12 of FIG. 1. The media drive 48 andthe circuit board 72 are mounted to a sled 74, which, when inserted intothe rear receptacle 20, engages conventional left- and right-siderunners 76, which are mounted to the inside of the chassis 16. Aconnector 78 is mounted to the circuit board 72 and is coupled to theinterface circuit on the circuit board 72. The connector 78 mates with aconnector 80—which is mounted to the circuit board 68 and is coupled tothe library control circuit on the circuit board 68—when the module 70is fully inserted within the rear receptacle 20. Thus, the connectors 78and 80 provide a communication path between the library control circuitand the interface circuit. A connector 82, which is mounted to thecircuit board 72, provides a communication path between the interfacecircuit and the computer 12. Furthermore, when the module 70 is insertedwithin the rear receptacle 20, an opening 84 of the media drive 48,which receives the storage medium, is located below the slots 30 so thatthe storage-medium transporter can load and unload a storage medium intoand from the media drive 48 via the opening 84 without interference fromthe slots 30. Therefore, the top-bottom sensor assembly 36 is located toalso generate the second optical beam across the opening 84, so that acartridge sticking too far out of the opening 84 will break the secondbeam.

Because the module 70 is easily removable and insertable, the operatoror a technician can easily modify the library 14 at the factory or inthe field to meet a customer's specific requirements. For example, theoperator or technician can modify the interface protocol and the type ofthe drive 48 by merely inserting into the rear receptacle 20 anothermodule 70 having the appropriate media drive 48 and circuit board 72.Different modules 70 can be provided for virtually all of theconventional interface protocols, including ultra-wide, fast SCSI,single-ended SCSI, differential SCSI, or fiber-channel.

Furthermore, the removable module 70 allows one to manufacture a singleversion of the library 14 base unit, which includes all parts of thelibrary 14 other than those included as part of the module 70. Thus,because only different versions of the module 70 need be manufactured tomeet a customer's specific interface and drive requirements, the costsand complexities of the manufacturing process are significantly lessthan for libraries that do not include such a removable module.

A power supply 86 and a power connector 88 are also mounted within thechassis 16. When connected to an external power source (not shown inFIG. 2) via the connector 88, the power supply 86 provides power to thecircuit board 68, the drive assemblies 46, 55, and 60, and the sensorassemblies 28, 34, 36, 42, and 44, and to the media drive 48 and thecircuit board 72 when the module 70 is installed within the rearreceptacle 20.

FIG. 3 is a schematic block diagram of the electronic circuitry of thelibrary 14 of FIG. 2. But because the specific circuitry used withineach of the blocks is conventional, it is not discussed in detail.

This circuitry includes an interface circuit 90 and a media drivecircuit 92. The circuit 90 communicates with the computer 12 of FIG. 1via the connector 82 and is located on the circuit board 72, which, asdiscussed above in conjunction with FIG. 2, is located on the removablemodule 70. The media drive circuit 92 communicates with the interfacecircuit 90, and may be located entirely within the media drive 48 ofFIG. 2, entirely on the circuit board 72, or may have a portion that islocated within the media drive 48 and another portion that is located onthe circuit board 72.

A library control circuit 94 is located on the circuit board 68 of FIG.2 and communicates with the motors 52, 56, and 62, the sensor assemblies28, 34, 36, 42 and 44, and the power supply 86 all of FIG. 2, and akeyboard display assembly 96, which allows the operator to input data orcommands directly into the library 14 and to select different softwareoptions that the control circuit 94 supports. In one embodiment, thelibrary control circuit 94 includes one or more conventionalmicroprocessors or microcontrollers (not shown in FIG. 3). Furthermore,the connectors 78 and 80 allow power, control information, and data tobe passed back and forth between the library control circuit 94 and theinterface circuit 90.

In one embodiment, the interface circuit 90 includes a host interfacecircuit 98 and a library interface circuit 100. The host interfacecircuit 98 is coupled to the computer 12 via the connector 82, and isalso coupled to the library interface circuit 100, which is coupled tothe library control circuit 94. The media drive circuit 92 is coupled tothe host interface circuit 98, and in one embodiment is also coupled tothe library interface circuit 100.

FIG. 4 is an isometric view of a storage-medium transporter 102, whichis mounted in the chassis 16 of FIG. 2 between the mailbox 22 and theslots 30 such that a front opening 104 of the transporter 102 faces themailbox 22 and a rear opening 106 faces the slots 30 and the rearreceptacle 20. In one embodiment, the transporter 102 moves verticallyup and down and is constructed to bi-directionally transport amagnetic-tape cartridge, such as a DLT cartridge (such as shown in FIG.7), through a passageway 107 extending between the front and rearopenings 104 and 106. Therefore, although the transporter 102 can beconstructed to transport any type of storage medium, for examplepurposes, the embodiment of the transporter 102 hereinafter describedwill be for transporting a DLT cartridge.

The transporter 102 includes spring-loaded front and rear roller arms108 and 110, which each pivot between an opened and closed position torespectively release and grasp a cartridge. Each of the roller arms 108and 110 carries a respective portion of a roller mechanism 112, whichincludes a number of rollers 114. The rollers 114 are rotationallyintercoupled by meshing gears 116. The roller drive shaft 58 rotates aroller drive gear 118, which in turn drives the rollers 114 via thegears 116. The shaft 58 has a slot or keyway 120, which engages a splineor key along the inner circumference of the gear 118 to allow the gear118 to move freely up and down on the shaft 58 as the transporter 102moves up and down.

The transporter 102 is fixedly attached to the belt assembly 50 by beltcouplings 122. Furthermore, a support shaft 124 guides and stabilizesthe transporter 102 as it is moved up and down along the shaft 124 bythe belt assembly 50.

The transporter 102 also includes a cam mechanism 126, which includes alatch-release-and-front-roller-arm cam 128, afinal-push-and-rear-roller-arm cam 130, and cam intercoupling gears 132,134, and 136. The cam drive shaft 64 rotates a cam drive gear 138, whichin turn drives the cam mechanism 126. Like the roller drive shaft 58 andthe roller drive gear 118, the cam drive shaft 62 has a keyway and thecam drive gear 138 has a key such that the cam drive gear 138 can movefreely up and down on the cam drive shaft 62 as the transporter 102moves up and down. The cam gear 136 includes at least one homing opening140, which, when aligned with the optical beam generated by the camsensor assembly 44 of FIG. 2, indicates that the cam mechanism 126 is ina home position. Portions of the transporter 102 that are positionedbelow the gear 136 have openings that are aligned with the optical beamof the cam sensor assembly 44 such that when the opening 140 is in thehome position, the beam can pass through the opening 140 uninterrupted.

The transporter 102 also includes a latch-plunger assembly 142, whichreleases the latch mechanism 25 of FIG. 2 when the transporter 102 isremoving a cartridge from the mailbox 22. The transporter 102 alsoincludes a homing tab 144, which breaks the optical beam generated bythe vertical-position sensor assembly 42 of FIG. 2 when the transporter102 is in a home position.

Referring to FIGS. 2, 3, and 4, during operation of the library 14, theoperator inserts a cartridge into one of the slots 24 in the mailbox 22until the latch 26 of the slot stops the operator from inserting thecartridge any farther. Next, the transporter motor 52 rotates and thetransporter drive assembly 46 moves the transport 102 upwards until thehoming tab 144 breaks the beam generated by the sensor assembly 42.Then, the library control circuit 94 receives from the respectiveoptical sensor assembly 28 a signal that indicates that the cartridge iswithin the slot 24. The circuit 94 next controls the transporter motor52 to rotate a known number of steps so that the drive assembly 46 movesthe transporter 102 downward until the front opening 104 of thetransporter 102 is aligned with the slot 24 containing the cartridge.The counting of the steps may be conventional, or may take into accountthe backlash of the transporter drive assembly 46 as discussed below.

FIGS. 5A-5D show respective positions of the roller mechanism 112 andthe cam mechanism 126 during a load/unload sequence where thetransporter 102 retrieves a cartridge 146 from one of the storage slots24 of FIG. 2 and loads the cartridge into one of the slots 30 or themedia drive 48 of FIG. 2.

Referring to FIG. 5A, at some time before the transporter 102 moves intoits home position, the cam motor 62 rotates until the cam mechanism 126is in the home position. In this position, both of the front and backroller arms 108 and 110 are in their respective opened positions suchthat as the transporter 102 moves, the arms 108 and 110 will not contacta cartridge 146 that is in one of the slots 24 or 30. As stated above,the circuit 94 of FIG. 3 determines that the cam mechanism 126 is in thehome position when the optical beam generated by the sensor assembly 44of FIG. 2 is unbroken. In one embodiment, the gear ratios of the cams128 and 130 and the gears 132, 134, and 136 are such that the cammechanism 126 is in the home position when either of the two openings140 is aligned with the optical beam.

Still referring to FIG. 5A, it is known that in most gear systems, suchas the cam mechanism 126, there occurs a phenomenon known as backlash.The degree of backlash is the amount of free play between the gears asthey rotate from one direction to another direction. That is, themanufacturing tolerances of the gear-tooth widths are often such thatwhen the teeth of one gear are entered between the respective teeth of ameshing gear, there are spaces between the adjacent gear teeth. Thus,before they engage, the gears must rotate slightly until one toothcontacts an adjacent tooth of a meshing gear. Therefore, because thenext position of the cam mechanism 126 is determined by counting thenumber of steps that the cam motor 62 of FIG. 2 rotates from the presentposition, the circuit 94 of FIG. 3 may be programmed to account for thebacklash when the rotational direction of the present rotation of thecam motor 62 is different than the rotational direction of theimmediately previous rotation.

In one embodiment, the circuit 94 accounts for backlash by storing thenumber of rotational steps of the cam motor 62 needed to compensate forthe backlash. This number then becomes part of the total number of stepsrequired to rotate the cam motor 62 so that the cam mechanism 126 willbe in the desired position relative to the present position. Thebacklash number may be empirically determined, or may be determined foreach cam mechanism 126 by rotating the cam mechanism 126 in a firstdirection until the gears engage, rotating the cam mechanism in a seconddirection until the gears engage, and counting the number of steps thatthe cam motor 62 rotates in the second direction. For example, after thecam mechanism 126 is moved in a first direction into the home position,the circuit 94 counts the number of steps—the backlash number—that thecam motor 62 must rotate in the opposite direction to move the cammechanism 126 out of the home position. As discussed above, this type ofbacklash compensation can also be used in the transporter drive assembly46. But backlash is typically much less of a problem for a belt drive,and thus can often be ignored in a belt-driven assembly such as used forthe transporter drive assembly 46.

Referring to FIG. 5B, once the transporter 102 has been aligned with theappropriate slot 24 of FIG. 2, the cam motor 62 of FIG. 2 rotates theappropriate number of steps such that the cam mechanism 126 is in themailbox-unload position. In this position, the cam 128 causes thelatch-plunger assembly 142 to disengage the latch 26 of the slot 24 sothat the transporter 102 can unload the cartridge 146 from the slot 24.The cam 128 also causes the front roller arm 108 to close such that therollers 114 of the roller mechanism 112 engage the side of the cartridge146. The roller motor 56 of FIG. 2 then rotates a predetermined numberof motor steps to rotate the rollers 114 such that they approximatelycenter the cartridge 146 within the passageway 107 of the transporter102. In one embodiment, the circuit 94 of FIG. 3 compensates forbacklash in the roller mechanism 112 as discussed above for the cammechanism 126.

Still referring to FIG. 5B, the transporter motor 52 of FIG. 2 rotates apredetermined number of motor steps to move the transporter 102 up ordown as needed to align the cartridge 146 within the transporter 102with its destination, which is either one of the slots 30 or the opening84 of the media drive 48, all of FIG. 2. The rear roller arm 110 remainsopen so that as the transporter 102 moves, the roller arm 110 does notcontact another cartridge 146 that may be in another one of the slots 30other than the destination slot 30.

Referring to FIG. 5C, after the cartridge 146 has been aligned with itsdestination, the cam motor 62 of FIG. 2 rotates a predetermined numberof steps such that the cam mechanism 126 is in a media-drive/rear-slotunload position. In this position, the cam 128 disengages thelatch-plunger assembly 142 and opens the front roller arm 108.Furthermore, the cam 130 closes the rear roller arm 110. Once the rearroller arm 110 is closed, the roller motor 56 of FIG. 2 rotates apredetermined number of steps such that the rollers 114 move thecartridge 146 into its destination.

If, as shown in FIG. 5C, the destination is one of the slots 30 of FIG.2, then the circuit 94 of FIG. 3 monitors the sensor assembly 36 of FIG.2 to determine if the second optical beam that is directed across theopenings 40 of the slots 30 and the opening 84 of the media drive 48 isbroken or unbroken. If the beam is unbroken, then the circuit 94determines that the cartridge 146 has been fully inserted into thedestination slot 30. If the beam is broken, then the circuit 94 causesthe roller motor 56 to rotate additional steps until the rollers 114insert the cartridge 146 fully into the destination slot 30.Alternatively, instead of counting the number of steps that the rollermotor 56 rotates, the circuit 94 can cause the roller motor 56 tocontinue rotating until the beam is unbroken, thus indicating that thecartridge 146 has been fully inserted into the destination slot 30.

If, as shown in FIG. 5D, the cartridge destination is the media drive 48of FIG. 2, then the rollers 114 often cannot fully insert the cartridge146 into the opening 84 of the media drive 48. Thus, after the initialmoving of the cartridge into its destination as described in conjunctionwith FIG. 5C, the cartridge 146 is often inserted only part way into theopening 84. Therefore, the second optical beam is broken, and thecircuit 94 of FIG. 3 controls the cam mechanism 126 to perform anadditional step called the “final push.” During this step, the cammechanism 126 pushes the cartridge 146 the remaining way into theopening 84, or at least far enough into the opening 84 so that theconventional cartridge intake mechanism of the media drive 48 isactivated. Once activated, the intake mechanism retracts the cartridge146 the remaining way into the media drive 48. More specifically, thetransporter drive assembly 46 moves the cartridge transporter 102 suchthat the cam 130 is aligned with the opening 84 of the media drive 48.The cam 130 rotates in the direction shown by the arrow in FIG. 5D so asto open the rear roller arm 110 and push the cartridge 146 into theopening 84. In one embodiment, this is the only step where therotational direction of the cam mechanism 126, specifically therotational direction of the cam 130, is not arbitrary, but is in theindicated direction so that a gradually sloped surface 145 of the cam130 engages the cartridge 146 and provides a relatively smooth pushthereto. In another embodiment, the cam 130 is more symmetrically shapedsuch that it can rotate in either direction for the final push.

Although FIGS. 5A-5D describe a sequence of steps for transporting acartridge 146 from one of the slots 24 of FIG. 2 to one of the slots 30or the media drive 48, the sequence is reversed for transporting thecartridge 146 from the slot 30 or the media drive 48 to a slot 24.

FIG. 6 is an exploded isometric view of the latch mechanism 25, which issupported by a support wall portion 147 of the mailbox 22 of FIG. 2. Thelatch mechanism 25 includes a pivot pin 148, which extends through anopening 150 formed in each of latches 26. A latch spring 152 ispositioned between the back side of each latch 26 and a respectivespring receptacle 154, which is located on a mailbox support and jambmember 156 of the mailbox 22. For clarity, only one spring 152 and onereceptacle 154 are shown in FIG. 6. The latches 26 are biased by thesprings 152 to extend through respective latch openings 158 in a sideportion 160 of the mailbox 22. The latches 26 are pivoted back so as notto extend through the respective latch openings 158 when thelatch-plunger assembly 142 of FIG. 4 engages them.

A conventional DLT cartridge 146, such as shown in FIGS. 5A-5D, is shownin FIG. 7 with portions shown in phantom line. Although one embodimentof the library 14 is constructed to receive DLT cartridges, otherembodiments of the library 14 can be constructed to receive other typesof storage media such as 4 millimeter (mm) and 8 mm tape cartridges. Insuch embodiments, the mailbox 22 and the slots 30 of FIG. 2 areconstructed to respectively receive such other media cartridges, and therespective removable module 70 of FIG. 2 includes a media drive 48 foraccepting such cartridges.

FIG. 8 is an exploded isometric view of one embodiment of thekeyboard/display panel 96 of FIG. 3 and one embodiment of a doorassembly 162 for the library 14 of FIG. 1. The keyboard/display panel 96includes a conventional display 164 and conventional punch keys 166, andallows the operator to manually input data and instructions to thelibrary control circuit 94 of FIG. 3. The library control circuit 94 mayalso display a software menu from which the operator can select functionoptions with the keys 166.

The door assembly 162 includes a door 168 having hinge cylinders 170 anda cartridge-alignment protrusion 172, which engages the cartridge orcartridges 146 of FIG. 7 and ensures that they are fully inserted intothe slots 24 when the door 168 is closed. The door 168 may also includea lock 174, which impedes unauthorized access to the mailbox 22 and anycartridges 146 therein. The lock 174 may be a conventional key lock, ormay be an electronic lock that is controlled by the computer 12 of FIG.1 via the library control circuit 94 of FIG. 3.

The door assembly 162 also includes a hinge assembly 176, which includesa support plate 178, resilient extensions or fingers 180, and hingecylinders 182. The support plate 178 is attached to a forward-facingfront jamb portion 157 of mailbox jamb member 156, and the hingecylinders 170 of the door 168 are pivotally connected to the hingecylinders 182. The hinge cylinders 170 and 182 are retained in aninterlocked position by a hinge pin 184 extending therethrough. Thefingers 180 extend out from an edge of the support plate 178 and curvetowards the front side of the support plate 178. The hinge cylinders 182are attached between the ends of adjacent ones of the fingers 180. Inone embodiment, resulting spaces 183 are defined between adjacent onesof the fingers 180. The spaces 183 are shaped to allow the operator toposition a finger therein so that the hinge assembly 176 does not hinderthe operator when grasping the cartridge 146 to insert or remove thecartridge 146 from one of the slots 24. Furthermore, the fingers 180 arerelatively rigid and resist movement in a vertical direction to providesolid support for the weight of the door 168.

FIG. 9 is a top view of the door assembly 162, and shows variouspositions of the door 168 as it moves between opened and closedpositions. Referring to FIGS. 8 and 9, the hinge cylinders 170 and 182of the door assembly 162, and the hinge pin 184 which extendstherethrough, are offset laterally inward from the sidewall 188 of thelibrary chassis 16 so that the door 168 can be opened withoutencroaching on an adjacent rack space. Specifically, a hinged side 186of the door 168 is positioned at or inward from the sidewall 188 of thelibrary chassis 16 when the door is closed. Thus, when the door 168 isin the closed position, it covers virtually the entire front side of thelibrary 14, including the hinge assembly 176, without encroaching on thespace occupied by any adjacent rack-mounted components, such as anotherlibrary 14. Furthermore, as the door 168 is opened or closed, the hingeassembly 176, as discussed below, prevents the hinged side 186 of thedoor 168 from encroaching on the adjacent rack space by reducing thedistance that the hinged side 186 extends beyond the sidewall 188 ascompared with conventional hinges. In one embodiment, no part of thehinged side 186 extends beyond the sidewall 188 when the door 168 isopened, closed, or in any position therebetween.

FIGS. 10A-10C are cut-away top views of the door assembly 162 and thehinge assembly 176 when the door 168 is in a closed position,intermediate position, and opened position, respectively. Referring toFIG. 10A, the fingers 180 project forward from the support plate 178 andcurve laterally outward to position the hinge cylinders 182 spaced apartfrom the support plate 178 and to define a laterally open space 185therebetween. Referring to FIG. 10B, as the door 168 is rotated into theopened position, the hinged side 186 of the door 168 moves into thespace 185 so that the door 168 may be opened and closed uninhibited bythe offset hinge-line arrangement used. Specifically, fingers 180 areflexible in the outward (away from the chassis 16) and inward (towardthe chassis 16) directions such that as the hinged side 186 engages thefront of the plate 178, the fingers 180 flex to allow the hinged side186 to slide against the plate 178 as the door 168 moves between closedand opened positions. Furthermore, in one embodiment, the spring forcewith which the fingers 180 push the hinged side 186 against the plate178 is sufficient for the door 168 to be stable in many partially openpositions. Referring to FIG. 10C, when the door 168 is fully open, thefingers 180 return to their unflexed positions (as in FIG. 10A), and thehinged side 186 is parallel or approximately parallel to and abuts theplate 178. Because moving the door 168 toward the closed position causesthe fingers 180 to flex outward and force the side 186 against the plate178, the hinge assembly 176 tends to hold the door 168 open againstunintentional closing.

Referring to FIGS. 9 and 10C, in some embodiments, depending on theangle the side 186 makes with a door front face 190, the door 168 mayopen more than 90° such that portions of the front face 190 may extendbeyond the chassis sidewall 188. But this typically does not cause thedoor 168 to significantly encroach upon an adjacent space, because anadjacent component typically does not extend forward far enough forthese encroaching portions of the front face 190 to contact the adjacentcomponent. But even if it is possible to open the door 168 far enough toencroach, the door 168 need not open to more than an approximately 90°position—which is not encroaching—to allow the operator to insert andremove a cartridge 146 from the mailbox 22.

Referring to FIGS. 8 and 10B, in one embodiment, the fingers 180 areformed from a conventional plastic. But it has also been found that withrepeated openings and closings of the door 168, the fingers 180 maybecome deformed from their desired shape. That is, the resiliency of thefingers 180 may be too low, and thus the hysteresis of the fingers 180may be too high, for the fingers 180 to maintain their desired shape.Therefore, a metal spring member 192 overlaying the fingers 180 is usedto increase the effective resiliency of the fingers 180. The springmember 192 includes a plate 194 that is installed between the jambportion 157 of the mailbox member 156 and the hinge plate 178. Thespring member 194 also includes fingers 196, which extend around andoverlay the fingers 180. The spring member 194 is formed from amaterial, such as metal, that has a significantly higher resiliency thanthe material from which the fingers 180 are formed. Thus, the fingers196 of the spring member 194 force the respective fingers 180 back intotheir desired shapes after each opening and closing of the door 168. Anactual door assembly 162 in accordance with this embodiment has beentested over a million times, and has been found to be very reliable.

Furthermore, referring to FIGS. 8, 9, and 10 c, it is noted that withthe described door assembly 162, if the door 168 is pressed open fartherthan the intended fully open position, the opening force applied to moveit beyond the fully open position will be resisted by the spring forceof the fingers 180, and if present, the spring member 192. Thus, thefingers 180 and 196 can bend under this excess opening force without thehinge assembly 176 breaking.

FIG. 11 is an isometric view of ten of the libraries 14 of FIG. 1mounted in a rack 200. As shown, neither the opened nor closed doors 168of the libraries 14 encroach on the respective rack spaces occupied bythe adjacent libraries 14.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

What is claimed is:
 1. A library for storing a cartridge of data-storagemedia, comprising: a removable module; a chassis having a modulereceptacle sized to removably receive the removable module; cartridgestorage slots disposed within the chassis; a media drive disposed withinthe removable module and having a drive opening, the media driveoperable to receive and release the cartridge through the drive opening;a cartridge transporter disposed within the chassis and operable totransport the cartridge between one of the cartridge slots and the mediadrive when the module is disposed within the module receptacle; alibrary control circuit disposed within the chassis and coupled to thecartridge transporter; an interface circuit disposed within theremovable module and coupled to the media drive, the interface circuitbeing operable to interface with a host computer that is external to thechassis, the media drive and interface circuit being movable as a unitwith the removable module; a first connector coupled to the interfacecircuit and carried by the removable module for movement therewith; anda second connector coupled to the library control circuit and positionedat the module receptacle to be connected to the first connector when theremovable module is received in the module receptacle to couple theinterface circuit to the library control circuit.
 2. The library ofclaim 1 wherein the second connector is supported by the chassis.
 3. Thelibrary of claim 1 wherein the first connector moves with the removablemodule as a unit along an inward path when the removable module is movedinto the module receptacle and the second connector is positioned alongthe inward path to be engaged by and connected to the first connector asthe removable module is being moved into the module receptacle, andwherein the first connector moves with the removable module as a unitalong an outward path and disconnects from the second connector as theremovable module is being moved out of the module receptacle.
 4. Alibrary for storing a cartridge of data-storage media, comprising: aremovable module; a chassis having a module receptacle sized toremovably receive the removable module; cartridge storage slots disposedwithin the chassis; a media drive disposed within the removable moduleand having a drive opening, the media drive operable to receive andrelease the cartridge through the drive opening; a cartridge transporterdisposed within the chassis and operable to transport the cartridgebetween one of the cartridge slots and the media drive when the moduleis disposed within the module receptacle; a library control circuitdisposed within the chassis and coupled to the cartridge transporter; aninterface circuit disposed within the removable module and coupled tothe media drive, the interface circuit being operable to interface witha host computer that is external to the chassis, the media drive andinterface circuit being movable as a unit with the removable module; andmeans for coupling the interface circuit to the library control circuitwhen the removable module is received in the module receptacle and fordecoupling the interface circuit from the library control circuit whenthe removable module is removed from the module receptacle.
 5. A libraryfor storing a cartridge of data-storage media, comprising: a sled havinga first signal connector and a host signal connector, the first signalconnector being carried by the sled for movement therewith; a chassishaving a sled receptacle that is constructed to allow insertion andremoval of the sled therein, the sled receptacle having a second signalconnector positioned to mate with the first signal connector when thesled is inserted into the sled receptacle and configured to disconnectfrom the first signal connector when the sled is removed from the sledreceptacle; cartridge storage slots disposed within the chassis; a mediadrive mounted within the sled for movement therewith as a unit andhaving a cartridge receptacle; a cartridge transporter assembly mountedwithin the chassis; a library control circuit mounted within the chassisand coupled to the cartridge transporter assembly and to the secondsignal connector; and an interface circuit mounted within the sled formovement therewith as a unit and coupled to the media drive, to thefirst signal connector, and to the host signal connector.
 6. A libraryfor storing a cartridge of data-storage media, comprising a chassis anda module, the chassis having: a module receptacle constructed to allowinsertion of the module into and removal of the module from the modulereceptacle; cartridge storage slots disposed within the chassis; acartridge transporter disposed within the chassis and operable totransport the cartridge; and a library control circuit disposed withinthe chassis and coupled to the cartridge transporter; and the modulehaving: a media drive mounted within the module, the media drive beingoperable to receive and release the cartridge, the cartridge transporterbeing operable to transport the cartridge between one of the cartridgeslots and the media drive when the module is inserted into the modulereceptacle of the chassis; an interface circuit disposed within themodule and coupled to the media drive, the interface circuit beingoperable to interface with a host computer that is external to thechassis, the media drive and interface circuit being movable as a unitwith the module upon insertion into or removal from the modulereceptacle of the chassis; and means for coupling the interface circuitto the library control circuit when the module is inserted in the modulereceptacle of the chassis and for decoupling the interface circuit fromthe library control circuit when the module is removed from the modulereceptacle of the chassis.
 7. The library of claim 6 wherein the meansincludes a first connector coupled to the interface circuit and carriedby the module for movement therewith as a unit upon insertion into orremoval from the module receptacle of the chassis; and a secondconnector coupled to the library control circuit and positioned at themodule receptacle to be connected to the first connector as the moduleis being inserted into the module receptacle to couple the interfacecircuit to the library control circuit.